Exercise Can Cut Breast Cancer Risk in
Women

Researchers from the University of Buffalo
in New York found the strongest protective effect against cancer among women
who reported engaging in a strenuous exercise regime 20 years previously.

Those who reported an average of 3.5 hours
per week of sweat-producing physical activity during this time halved their
chances of developing breast cancer later in life, said the researchers.

Study lead author Dr. Joan Dorn, an
assistant professor of social and preventive medicine, and colleagues,
re-analysed data from a diet study of U.S. women between the ages of 40 and 85,
conducted from 1986 to 1991.

The study involved 740 menopausal and
postmenopausal women with breast cancer, and 810 postmenopausal controls. They
were asked how regularly they had spent time exercising to the point of
breaking into a sweat two, 10 and 20 years prior to the interview and when they
were 16 years old.

The results showed that exercise produced
modest protective effects for both premenopausal and postmenopausal women who
were active at any one time period. Dorn said postmenopausal women who were
active at all four time periods had a 50 percent lower risk than their peers.

However, particular significance seemed to
apply to being active at a point 20 years in the past, because all women
exercising at this point halved their risk of developing breast cancer. In
addition, those active at the age of 16 reduced their risk by 35 to 45 per
cent.

Dorn suggested that these particular time
points might apply to significant physiological events in women's lives, such
as a first pregnancy.

Writing in the journal Medicine and Science
in Sports and Exercise, she said, "It's possible that strenuous exercise during
this period of a woman's life has an impact on breast cancer by favorably
affecting a hormonal milieu in the process of change.

"These results, combined with what we know
about the benefits of physical activity in protecting against other chronic
diseases, are enough to tell women to get out there and get some exercise."